Unidentified factors are considered the explanation for infertility when semen in the man and ovulation and fallopian tubes in the woman are normal.
When no explanation for infertility is identified, the following approach is used:
If clomiphene plus hCG is unsuccessful, women are sometimes given human gonadotropins (see Infertility: Human gonadotropins) before assisted reproductive techniques are tried. Women have the same chance of pregnancy (about 65%) whether in vitro fertilization is done immediately after unsuccessful treatment with clomiphene plus hCG or whether human gonadotropins are given next, before in vitro fertilization is tried. However, women become pregnant more quickly and are less likely to have a pregnancy with three or more fetuses when in vitro fertilization is done immediately after unsuccessful treatment with clomiphene plus hCG than when human gonadotropins are given next.
Last full review/revision February 2013 by Robert W. Rebar, MD